import asyncio

# 模拟流式返回
async def call_model_stream(model: str, message: str, session_id: str = None):
    # 这里可以根据 model 选择不同模拟方法
    response = f"[模拟 {model} 回复]: {message[::-1]}"  # 反转字符串模拟
    for char in response:
        await asyncio.sleep(0.05)  # 每个字符间隔
        yield char
